My greatest mistake: Boris Johnson, MP for Henley and editor of 'The Spectator'

My mistakes are too numerous to list in full, but one stands out that still makes me hang my head in shame. It was when I was working for the Wolverhampton Express and Star, and I wrote a piece about unemployment in Wolverhampton. It was the late 1980s, when unemployment was still pretty severe, and a lot of people were living in wretched conditions.

I had discovered a lawnmower shop that needed sales assistants, but no one was applying for the job. I couldn't understand it and wrote this irate comment piece about people scrounging benefits. I'd been in Wolverhampton only about a month, and it was unsurpassed right-wing drivel. I suppose it could be intellectually justified, but none the less it was condescending, and I felt afterwards like an Oxbridge graduate who had just arrived and was declaring everyone shirkers. I very much regret that.

I think anything to do with academic reputation or religion is the worst thing for me. I once went to cover the pilgrimage at Walsingham and referred to the image of the Virgin Mary as a bobbing doll – it was on the front page of The Times, and the Anglo-Catholics were furious.

I think my biggest cock-up, though, was when I first joined The Times and discovered that the site of Edward II's Rose Palace had been found on the banks of the Thames. It was a world exclusive, but I needed to find out more about Edward II – all I knew about him was that he had a catamite, Piers Gaveston, and that he was murdered in a castle.

I was desperate to get hold of a historian who could help me, but the only one I knew was my godfather Colin Lucas, a very distinguished man who is now vice-chancellor of Oxford University. He was actually an expert on the French Revolution, not medieval England, but I rang him and he obligingly gave me some quotes about Edward II. The trouble was that somewhere in my copy I managed to attribute to Colin the view that Edward II and Piers Gaveston would have been cavorting together in the Rose Palace. Unfortunately, some linkside don at a provincial university spotted that by the time the Rose Palace was built, Piers Gaveston would long have been murdered. It was very nasty. Colin hadn't quite said that, and now his academic reputation was on the line.

It was extremely difficult, and I had absolutely no idea what to do. I was 23, overcome with guilt and shame that this error – this howler of mine attributed to Colin – had crept on to the front page of The Times, which was holy territory for me. So I made matters worse. I wrote a further story saying that the mystery had deepened about the date of the castle.

It was a complete nightmare of a disaster, and to make it even worse, that very week Colin was trying to become master of Balliol College. He later succeeded – but not that time. Of all the mistakes I've made, I think that takes the biscuit.